Tag Archives: climate

Compound Fluvial-Coastal Flood Adaptation

PI Philip Orton, Stevens Institute of Technology

Co-PI Franco Montalto, Drexel University 

Co-PI Marc Cammarata, Philadelphia Water Department 

Additional team members: Julia Rockwell (PWD), Korin Tangtrakul (Drexel), Kazi Mita (Stevens)

Funding agency/program:  National Oceanic and Atmospheric Administration, Climate Program Office, Coastal Ocean Climate Applications (COCA)/Sectoral Applications Research Program (SARP)

Project Period:  September 2019 to August 2021

Abstract

Compound flooding is the combination of rainfall-induced flooding with storm surge induced flooding, and is currently inadequately considered nationwide in both flood risk assessment and forecasts. It is well-established that coastal floods are becoming more frequent, and the U.S. Northeast has seen a substantial increase in intense rainfall events in recent decades, likely as a result of climate change. In many U.S. cities, coastal and fluvial floods merge in estuaries, causing a compounded problem, and the coincident occurrence of extreme rain and surge is growing at many locations. However, little research has been performed to improve our understanding of compound flooding.

An ideal location to investigate this problem, Eastwick is a low-lying neighborhood in South Philadelphia situated near the Delaware River at the confluence of Darby and Cobb’s Creeks. It is in close proximity to the 1.2 km2 John Heinz National Wildlife Refuge, two federal Superfund sites, a series of oil refineries, and the Philadelphia International Airport, and meets the EPA criteria for an Environmental Justice community, with a majority (76%) of its population being African American, and pockets of low income residents. Triggered by rainfall, coastal surges pushing up the tidal portion of the Delaware River, or some combination of the two, flooding has long been one of the biggest problems facing this community.

The proposed research will inform climate risk management and adaptation decision-making regarding flooding in Eastwick, and will be performed by researchers from two universities and the Philadelphia Water Department (PWD). The project will include four core areas of science, as well as a community engagement process, strong coordination with decision makers and a specific focus on two ongoing city planning initiatives. The core compound flood science research areas include flood modeling, extreme value analysis, climate-impact assessment, and adaptation benefit-cost analysis. The engagement process will consist of two community workshops, including collaborative design of flood adaptation scenarios and a socially-sourced validation of the flood modeling. Coordination with decision makers will occur through an advisory panel, project webinars, and the activities of our team members at the PWD.

The proposed research will strongly further NOAA and COCA/SARP interests relating to climate change. It presents a framework and detailed technical approach for addressing both the communication of risk and the economics of adaptation to compound flooding and climate change. An important additional component of the planned research is to compare our detailed analyses to simplified approaches, to improve the transferability of the work to other communities with similar challenges. The advancement of scientific understanding, prediction and communication of compound flooding will help enable effective decisions, and our development and dissemination of modeling, statistical hazard analysis and benefit-cost analysis tools will have a nationwide impact on resilience.

Introduction

Eastwick is a low-lying community in South Philadelphia that floods frequently yet lacks sufficient information on flood risk or adaptation. It meets the EPA criteria for an Environmental Justice community, with a majority (76%) of its population being African American, and pockets of low income residents. The community is situated near the Delaware River at the confluence of Darby and Cobb’s Creeks, and in close proximity to the 1.2 km2 John Heinz National Wildlife Refuge. Unfortunately, Eastwick also happens to be located next to portions of the Lower Darby Creek Superfund Site, increasing the health risks posed by any flooding that occurs in this area.

Flooding has long been one of the biggest problems facing Eastwick, the lowest-lying community in Philadelphia (University of Pennsylvania, 2017). Eastwick’s floods can be purely due to rainfall, purely due to high coastal sea levels pushing up the tidal Delaware River, or they can be compound flooding (Moftakhari et al., 2017; Wahl et al., 2015), the merger of the two (U.S. Army Corps of Engineers, 2014).  As such, the community exemplifies a common problem faced by low-lying coastal neighborhoods located at the downstream end of coastal urbanized watersheds found across the nation. Eastwick has been designated by FEMA as a Special Flood Hazard Area. In 1999, for example, Hurricane Floyd deposited 25 cm of rain in the Darby Creek watershed and pushed a 0.85 m surge up the Delaware River, creating such severe flooding that residents had to be rescued by rowboat.  After Hurricane Irene’s (runoff-induced) flood and just before Hurricane Sandy’s (surge-induced) flood, the Mayor called for a comprehensive solution to Eastwick’s flooding problems, yet to date no comprehensive mitigation plan for the neighborhood has been developed.

Compound flooding is currently inadequately considered nationwide in both flood risk assessment and modeling activities. Neither FEMA’s maps, nor NOAA’s forecasts address compound flooding because they address runoff-induced or surge-derived flooding separately (e.g., Corelogic, 2017a; Moftakhari et al., 2017; Orton et al., 2012). For example, Philadelphia is ranked as being the metro area with the 11th-highest hurricane storm surge risk in the US (Corelogic, 2017b), but that study did not account for rainfall. Flood modelers often either assume constant stream flow, if they are simulating surge-derived floods, or a static coastal water level if they are simulating runoff-induced riverine floods (e.g., U.S. Army Corps of Engineers, 2014). Holistic simulation and probabilistic assessment of compound flooding is thus essential to “risk characterization” and to “the development of innovative, applicable, and transferable approaches for decision making” in urban coastal communities across the nation (two key goals of the CSI program).

Proposed study and objectives

The overriding objective of the proposed research is to inform climate risk management and decision-making regarding flooding in Eastwick. The proposed research activities will be integrated into two ongoing community planning initiatives: (1) the City-wide Flood Risk Management Task Force which was first convened in 2015 “to address the circumstances of flooding as it impacts various Philadelphia neighborhoods” including Eastwick (PWD, 2017a) and (2) the Lower Eastwick Public Land Strategy (LEPLS), a planning effort that has developed and will now begin to implement a vision for Eastwick’s vacant and publicly-owned land (RDA, 2017). Our interactions with the Task Force will be facilitated principally by project partner Philadelphia Water Department (PWD) with Co-PI Joanne Dahme and PWD project manager Julia Rockwell, while our interaction with the LEPLS (Figure 1) will be through our partners at Keystone Conservation Trust and the Eastwick Friends and Neighbors Coalition.

Flow Chart 3a

Figure 1:  Diagram of the proposed COCA/SARP project (top) as well as the timeline of projects with which the study would connect or leverage (bottom).

 

The research team will improve an existing dynamic model of compound flooding in Eastwick developed by the project team and use it in conjunction with ongoing and proposed new stakeholder activities in several inter-related ways. The land use strategies developed by the LEPLS team will be incorporated into the model domain, ensuring that future climate impacts and adaptation scenarios respond to the community’s expressed aspirations and goals regarding local land cover and land use. New workshops planned by the project team will be used to validate retrospective model simulations with local knowledge regarding the location, timing and severity of historical flooding in the community (a “social validation”).  These workshops will also source community-guided green and grey flood adaptation measures across the watersheds and waterfronts (e.g. Figure 2). The efficacy of these measures for mitigating flooding will be quantified with dynamic flood modeling of historical and synthetic flood events across a wide range of return periods (e.g. Figure 3). Damage computations for flooding and benefit-cost ratios will be computed using improved city data within FEMA’s HAZUS software.

eastwick_workshop_pic

Figure 2:  Co-PI Montalto and his students listening to community leaders with Eastwick Friends and Neighbors Coalition (EFNC) at last year’s flooding workshop.

These activities will be coordinated through and at times conducted during regularly scheduled meetings of the City-wide Task Force, minimizing the time commitment that our engagement activities will have on local stakeholders, while also ensuring participation of a diverse and representative group of intended beneficiaries in the research. This synchronization will ensure that the research outputs are both timely and germane, given other planned activities in this dynamic community.

In this way, we will test innovative, broadly applicable approaches for flood modeling, flood risk assessment, benefit-cost analysis of compound flood risk reduction scenarios. Key contributions of the research to the science of climate adaptation and engagement will be: a) an evaluation of the proposed stakeholder-engaged modeling approach as a means of communicating complex probabilistic, multi-source flood risks to a vulnerable community, b) development of a workshop framework that can be used to explore the advantages and disadvantages of alternative adaptation strategies under a wide range of compound flood risk scenarios.

sandrene

Figure 3: Example of modeled flooding (shaded water depth in feet) for a synthetic storm event with Hurricane Sandy’s Delaware River water levels combined with Hurricane Irene’s Cobbs-Darby streamflows.  Eastwick spans the top-right to the center-right.

 

References

Corelogic. (2017a). Storm Surge Inundation vs Freshwater Flooding Report.   Retrieved August 8, 2017, from http://www.corelogic.com/about-us/researchtrends/storm-surge-inundation-vs.-freshwater-flooding-report.aspx?WT.mc_id=crlg_170601_97ewN#.WYt9kVF95PY

Corelogic. (2017b). Storm Surge Risk Report.   Retrieved August 9, 2017, from http://www.corelogic.com/about-us/researchtrends/storm-surge-report.aspx?WT.mc_id=pbw_170530_iRNG1

Moftakhari, H. R., Salvadori, G., AghaKouchak, A., Sanders, B. F., & Matthew, R. A. (2017). Compounding effects of sea level rise and fluvial flooding. Proceedings of the National Academy of Sciences, 114(37), 9785-9790.

Orton, P., Georgas, N., Blumberg, A., & Pullen, J. (2012). Detailed modeling of recent severe storm tides in estuaries of the New York City region. Journal of Geophysical Research, 117, C09030. doi: 10.1029/2012JC008220

PWD. (2017a). Citywide Flood Risk Management Task Force.   Retrieved August 9, 2017, from http://www.phillywatersheds.org/category/blog-tags/citywide-flood-risk-managment-task-force

University of Pennsylvania. (2017). Researchers and Residents Explore ways Eastwick Floods and Ideas for Mitigation.   Retrieved May 19, 2017, from https://www.sas.upenn.edu/urban/news-events/news/researchers-and-residents-explore-ways-eastwick-floods-and-ideas-mitigation

U.S. Army Corps of Engineers. (2014). Eastwick Stream Modeling and Technical Evaluation Philadelphia, Pennsylvania, Philadelphia District, North Atlantic Division.

Wahl, T., Jain, S., Bender, J., Meyers, S. D., & Luther, M. E. (2015). Increasing risk of compound flooding from storm surge and rainfall for major US cities. Nature Climate Change, 5(12), 1093-1097.

 

 

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Collaborative Climate Adaptation Planning for Urban Coastal Flooding

PIs:  Philip Orton, Alan Blumberg, Peter Rowe (New Jersey Sea Grant Consortium), Tanya Marione-Stanton (Jersey City Department of City Planning); Partners:  Sergey Vinogradov, Naomi Hsu, Steve Eberbach, Jeff Wenger

Funding agency:  NOAA Sea Grant

Project period:  July 2013 – January 2015 (completed)

IMG_5013

Photograph of Philip Orton presenting at City Hall, at one of the public meetings where Jersey City Planners and Stevens Researchers presented options for reducing the chances of storm surge flooding.

Coastal cities across the country are weighing their options for adapting to rising floods, yet there is limited quantitative information available to help make these decisions. This project was a collaboration between coastal flooding scientists and Jersey City planners to develop and test several options for adapting the region’s urban coasts to flooding and sea level rise. Jersey City (JC) is the second-most populous city in NJ, yet has 43% of its land within the new FEMA 100-year flood zones. We leveraged pre-existing storm surge modeling and flood zone mapping to quantify the performance of a set of storm surge protection measures for Jersey City.

Outcomes and outputs from the research included: (1) regional flood zone maps that account for future sea level rise and storm climatology changes, (2) model-based map animations of how floodwaters enter JC to help understand how the pathways can be blocked, (3) a report of a collaboratively determined set of coastal adaptation options, and their performance with sea level rise, (4) an outreach workshop where we presented the project’s results to additional regional stakeholders, and (5) a transferable, peer reviewed and published adaptation planning and evaluation framework. Lastly, and still an ongoing process, it is our goal to help Jersey City, and possibly additional area cities, to implement climate change planning policies to adapt to coastal flooding.

This framework can also be utilized for many other U.S. coastal regions – anywhere that hydrodynamic models are already being used to simulate storm surges or map flood zones. FEMA has embarked on an ambitious effort to re-evaluate the nation’s coastal flood zone maps, and many of these regional efforts are utilizing these models. Many areas also have storm surge forecast models in place that can be similarly used for adaptation studies.

Project Results Summary

Computer storm surge simulations were used to map the effect of projected sea level rise on 100-year flood zones and to show the water pathways that flooded Jersey City during Hurricane Sandy, all useful information for planning measures that can prevent flooding.

Animation of modeled Hurricane Sandy flooding entering downtown Jersey City

Street-valley resolving animation of modeled Hurricane Sandy flooding entering downtown Jersey City (Blumberg et al. submitted). Color shading indicates floodwater depths over ground (legend on bottom right).

In several collaborative meetings, a broad set of realistic coastal protection measures and broad strategies were developed. Here is one example, a surge barrier that helps block a storm surge but could also be closed at low tide to create a rainwater basin for helping reduce the more frequent problem of rainfall flooding at high tide.

Illustration of one of 27 flood protection components, a surge barrier at the Tidewater Basin, south of downtown Jersey City

Illustration of one of 27 flood protection components, a surge barrier at Morris Canal Basin (aka Tidewater Basin), south of downtown Jersey City

This image comes from a partner project by Michael Baker Jr. Inc, and the report for that project is available here and includes both visualizations of the adaptation strategies, as well as a scoping study of what would be needed to conduct a benefit-cost analysis for the plans.

The storm surge modeling was then used to evaluate the efficacy of each adaptation measure, as well as how sea level rise and climate change will affect performance.  A city-wide adaptation scenario that combines several of the individual adaptation measures is found to protect most areas of the city from all storm events tested, ranging from a severe nor’easter that occurred in 1992, to Hurricane Sandy plus 31” of sea level rise (a high-end projection for 2055).

figure_SC4_success

Flood elevation model results for Hurricane Sandy Control (left), the full adaptation scenario (center), and the difference. In the right‐side panel, white areas have flooding in the control run, and do not have flooding with the adaptation scenario (flooding is prevented).

Hurricanes of a higher flood level than Sandy are possible, though unlikely – based on our replication of the FEMA flood mapping study (with added sea level rise), the 14-foot protection elevation could be overtopped by storms today, with an annual probability of 0.3%, or by storms after 31” of sea level rise, with an annual probability of 1%. A partial adaptation plan of land elevation increases around planned projects leads to prevention of flooding for most neighborhoods for the #2 and #3 largest flood events of the past century, the 1992 nor’easter and Hurricane Donna, but does not provide protection against Hurricane Sandy, and only keeps certain neighborhoods dry for the other flood events (e.g. Donna) when we consider 31” of sea level rise.

Read the full report here.

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Climate Reconstruction for Long Island Sound Fisheries

Analyzing History to Project and Manage the Future: Simulating the Effects of Climate on Long Island Sound’s Physical Environment and Living Marine Resources

Lead PI:  Nickitas Georgas, Stevens Institute of Technology

Co-PIs:  Philip Orton, Alan Blumberg, Stevens Institute of Technology

Co-PI:  Penelope Howell, Connecticut Department of Energy and Environmental Protection

Associate Investigator:  Vincent Saba, Geophysical Fluid Dynamics Laboratory and NOAA National Marine Fisheries Service

Funding:  EPA Long Island Sound office, New York and Connecticut Sea Grant programs

This project is now completed and has a ResearchGate summary page that includes publication links.

 

SUMMARY

In this project, we will a) conduct a multi-decadal three-dimensional hindcast of Long Island Sound (LIS) to study hypothesized linkages between the Sound’s physical climate and its recent ecological response and b) project future impacts of climate change and variability on the LIS ecosystem and its living marine resources over the span of the 21st century through model development and synthesis.

NYHOPS 3D model domain showing simulated SST, surface currents, and wind barbs. From the Google Earth viewer of the NYHOPS operational forecasts www.stevens.edu/NYHOPS

Figure 1: NYHOPS 3D model domain showing simulated SST, surface currents, and wind barbs. From the Google Earth viewer of the NYHOPS operational forecasts.

Specifically, our objectives are to:

  1. Address the paucity of physical environmental data during Long Island Sound’s (LIS) observed warming trend and accompanying fisheries shift since the 1970s by running a hindcast of the LIS circulation using the New York Harbor Observing and Prediction System (NYHOPS), an operational, comprehensive, high-resolution, three-dimensional, numerical model (Figures 1-2).
  2. Explore climate-forced links between the physical and ecological environment of the Sound by studying the statistical correlations of historic ecological data (such as the fish trawl survey data) to the physical environmental data from the NYHOPS model with a goal to explain the recent ecological regime changes and,
  3. Project the impacts of climate change and variability on the Sound’s ecosystem and its living marine resources until the year 2100, by forcing NYHOPS with Intergovernmental Panel for Climate Change (IPCC)-class global climate models, creating NYHOPS-based predictions for LIS to the end of this century, and deducing future changes to the LIS ecological regimes.
Figure 2. A zoom of the NYHOPS domain that covers the Long Island Sound. Shown is simulated SST (colored background and legend on the upper left), a popup with data from a UCONN buoy used in the NYHOPS model, and instantaneous surface current vectors also from the NYHOPS model. Screenshot taken from the NYHOPS google earth viewer 9/26/2012 1900Z.

Figure 2. A zoom of the NYHOPS domain that covers the Long Island Sound. Shown is simulated SST (colored background and legend on the upper left), a popup with data from a UCONN buoy used in the NYHOPS model, and instantaneous surface current vectors also from the NYHOPS model. Screenshot taken from the NYHOPS google earth viewer 9/26/2012 1900Z.

Justification

Over the last few decades, the LIS ecosystem has undergone profound changes. Water temperature measurements at a LIS long-term station frequently used in ecosystem assessments (LISS 2010, Howell and Auster 2012, among others) have recorded a significant warming trend (1.46ºC increase from 1976 to 2010; Dominion Resources Services 2011). Concurrently, substantial changes have occurred in the community structure and abundance of living marine resources in LIS (Howell et al 2005; Howell and Auster 2012). A dramatic example is the American lobster (Homarus Americanus) collapse, initiated by the major die-off in 1999.  Although multiple factors may have been synergistically responsible for this collapse, the increase in bottom temperature was likely the major factor that caused an increase in the mortality rate of lobsters, especially egg-bearing females (Howell et al 2005). Interestingly, the lobster collapse was exclusive to southern New England waters south of Cape Cod. The lobster stocks and fisheries further north, particularly the Gulf of Maine, are thriving. Reported landings have been at record highs over the past decade (Thunberg 2007). Based on the CT DEEP trawl survey, there seems to have been a shift in adult lobster population (ALTC 2010), that has altered the area where young lobsters recruit (Kim McKown, pers. comm.).

Fisheries-independent trawl surveys in LIS have reported substantial changes in finfish community structure and abundance (Howell and Auster 2012). Correlated with the increase in the bottom temperature of LIS from 1984 to 2008, the seasonal mean catch of cold-adapted finfish [i.e. windowpane flounder (Scophthalmus aquosus), spotted hake (Urophycis regia)] has significantly decreased, while warm-adapted species [i.e. butterfish (Peprilus triacanthus), striped sea robin (Prionotus evolans)] have increased (Howell and Auster 2012). There appears to have been a cold to warm species regime shift in the 95 finfish species examined statistically separating the community seen in 1984-1998 compared to 1999-2008 (Howell and Auster 2012). Although this time-period may be too short to attribute to climate change, it is apparent that the ecosystem of LIS may have responded to a climate perturbation.

The aforementioned reports suggest a regime shift in both the climate and ecosystem of LIS occurring around 1998. Remarkably, there have been increasingly more studies reporting a 1998 regime shift in the climate and living marine resources of coastal and pelagic marine ecosystems in vastly different parts of the world. To name a few, these include the Bering Sea (Rodionov and Overland 2005), the North Pacific (Overland et al 2008), and the North Sea (Weijerman et al 2005). Therefore, there may be a large-scale climate teleconnection between the local LIS climate and the global climate, whether due to natural or anthropogenic climate perturbations.

The apparent sensitivity of LIS to climate warrants research that elucidates the specific processes that are associated with the ecosystem’s response to climate perturbations. This is especially critical for projecting the impacts of global climate change on the LIS ecosystem given the 2-3ºC increase in surface air temperature projected by climate models included in the IPCC fourth assessment report (Christensen et al 2007). In order to assess, understand, and project the biophysical and mechanistic underpinnings between climate and living marine resources of  LIS, a detailed, historical analysis of climate and living marine resources is first required. However, the historical three-dimensional physical data of LIS is very sparse and only provides a general warming trend based on a few stations (one of which is near a power plant) without details on the relationships between circulation, hydrology, high-resolution depth-profile data covering the entire area of LIS, and interaction with the shelf-waters outside of LIS. Our proposed research will attempt to fill in these gaps.

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